The new foamer of this invention advances the foammaking ingredients (water, air and surfactant) through a foamer with ingredients subjected to alternating pressure and expansion of the mixture of ingredients.
The mixture passages are tortuous, and in the preferred embodiment, by alternating increase and decrease in cross-section so that the mixture is successively expanded and contracted to facilitate the foam generation. The ingredients of the foam may be supplied to the upstream end of the foamer at uniform pressure to passages in the foamer, and these passages have a preferred construction of circles of subpassages that are in generally annular groups in which the inside and outside radii of the annulus alternately increases and decreases in diameter while the radial distance between the inner and outer circumferences of the annuli remain substantially unchanged.
As an annulus decreases in diameter, its cross-section becomes less, and the foam ingredients increase in velocity. This increase in velocity reduces the pressure in the fluid stream. At places where the annulus increases in cross-section, the velocity of the foam ingredients is reduced with resulting increase in the pressure in the fluid stream. This alternating decrease and increase in the pressure in the fluid stream generates the foam.
Foam made in the improved foamer of this invention can be delivered through pipes as long as 200 feet and at low velocity without breaking up into alternating slugs of foam and air as occurred with foamers of the prior art.
Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.